1. 侯 might be listed as "lord" in the dictionary, but "marquis" is a better translation. It can't really be used for something as big as the galaxy. From what I've seen, 支配者（しはいしゃ） is a common phrase for "ruler".

2. Your order is wrong for の. The modifier has to come first, so it's 銀河の支配者 (or 銀河の侯 if you still want to go with that).

3. You should at least put a comma after 私, but a particle (は or が) might work too. Depends on the context.

1. 侯 might be listed as "lord" in the dictionary, but "marquis" is a better translation. It can't really be used for something as big as the galaxy. From what I've seen, 支配者（しはいしゃ） is a common phrase for "ruler".

2. Your order is wrong for の. The modifier has to come first, so it's 銀河の支配者 (or 銀河の侯 if you still want to go with that).

3. You should at least put a comma after 私, but a particle (は or が) might work too. Depends on the context.

first I really want to thank you for your big help Yudan!

and as I understand from your 3rd point I need to add (ha) (,) or (ga) after watashi right!???

now...it would look like this 私は if I used ha!
and it would be like this 私が if I used ga!

just to make sure! both 私は and 私が means I am! right!???

I have a question...why don't I use わ (wa) instead of は(ha) or が(ga) ???

Both 私は and 私が would be acceptable in this situation. There are differences between the two, and I suggest you look them up (and memorize them, so you don't have to go back to the first page of your textbook or whatever every 10 minutes like I do.) However, neither of them really mean 'I am', and thinking so will cause confusion in the future. 私 simply means I, and は and が mark the topic.

私は銀河の支配者 would be "I (subject) ruler of galaxy.' Words such as 'am' (though this one does exist) and 'the' are thrown into the translation when it is converted to english, and are not actually a part of the original Japanese sentence.

I have a question...why don't I use わ (wa) instead of は(ha) or が(ga) ???

One of those unimportant reasons dating back into history, I'd assume. Wa is always written with は when it is used as a particle, for reasons I never bothered to find out.

私 without any particle would be acceptable as well. But I think discussions of this are really beyond the scope of this thread, because it is impossible to decide between 私, 私は, and 私が when you're dealing with a contextless nonsense phrase.